In printers, print heads are provided to fire droplets of ink onto print media. The fluid is provided in a cartridge. The cartridge may be separately provided from the print head, or may be integrated with the print head. In many cases, the cartridge is a consumable supply that can be exchanged with respect to the printer. In some cases, the cartridge is arranged to be refilled, for example while being mounted in the printer.
The pressure in the cartridge needs to be carefully controlled well because it has an effect on the fluid flow into and/or out of the print head. In turn, this may have an effect on fluid drop characteristics, which is one of the most important parameters of image quality.